Card punching dies



May 18, 1965 v. F. SQRENSEN CARD PUNCHING DIES 2 Sheets-Sheet 1 Filed March 12 1962 2 Sheets-Sheet 2 V. F. SQRENSEN CARD PUNCHING DIES May 18, 1965 Filed March l2, 1962 United States Patent ()filice 3,l83,75 7 Patented; May 18, 1965 3,183,757 CARD PUNCHING DIES Villy Frank Sprensen, 5 Maglekiidevej, Copenhagen, Denmark Filed Mar. 12, 1962, Ser. No. 178,797 Claims priority, application Denmark, Mar. 13, 1%1, 1,063/61 5 Claims. (Cl. 83690) This invention relates to a punching die or matrix element for use in the punching of rectangular holes in punched cards, and a punching die made from such elements.

Punching dies for the purpose in question usually consist of a cutting plate and two guiding plates, and constructions are known in which both the cutting plate and each of the two guide plates are composed of a plurality of thin laminae or sheets in which the number of rows of holes required for the die in question are punched, the said thin sheets being assembled by riveting to form a laminated plate of sufiicient thickness. The two guide plates of the die serve to guide the punches or needles which in co-operation with the third platethe cutting plate-serve to punch the holes in the cards.

These known punching dies suffer from several drawbacks. The making of the dies is very troublesome and time consuming because the holes of the very thin sheets have to be punched and will therefore usually not be accurate enough to permit the use, in the card punching tool, of absolutely identical punches for all of the holes. The punches must therefore be adapted individually to each of the holes which is a tedious and expensive work, practically preventing the making of dies for the punching of several columns of holes at a time. Owing to the many holes to be punched within a relatively small area of the sheets, these must be made from very soft steel since they will otherwise expand and become distorted by the liberation of so much material. On the other hand, the use of very soft steel results in a relatively short lifetime of the cutting edges of the cutting plate. When the cutting edges have become worn, it is not possible to reestablish them by surface grinding because the cutting plate, as mentioned, consists of very thin sheets and the rounding of the worn cutting edges extends the whole way through the thickness of the outermost sheet. Consequently, when the cutting edges of such a die have become blunt, the Whole of the die has to be discarded.

When the cutting edges of the cutting plate of a die of the type described have become blunt, the pressure to be used for the punching operation will become excessive and may result in breakage of the cutting plate owing to rupture of the narrow strips between the holes of adjacent columns, it being observed that an ordinary card punching die has about 1000 such strips having a thickness of only a few tenths of a millimeter. A contributory cause for such rupture is that the said narrow strips of the cutting plate have been weakened by the notch effect occurring in the punching of the holes in the sheets an account of the very sharp corners.

It is the object of the invention to remedy the above mentioned drawbacks. According to the invention, a punching die element for use in the punching of rectangular holes in punched cards, which die element may be used either as a guide plate or as a cutting plate, comprises a plurality of first steel bars of rectangular cross section placed side by side at a mutual spacing to form a grid, a plurality of grooves extending side by side transversely of said steel bars across at least one face of said grid, a second surface ground steel bar being press fitted in each of said grooves, the outer faces of said second bars and the adjoining faces of said first bars being surface ground in a common grinding operation to form a smooth grid face.

Such a punching die may easily be made with such accuracy that the holes formed in the die between the bars will be located at absolute equal mutual distances and will be absolutely identical in shape and size. Consequently, the punches to be used in combination with the die may be ground to precisely equal cross sectional dimensions whereby the time consuming manual adaptation of each punch to its corresponding hole is eliminated.

Moreover, the punching die according to the invention is very strong, because the principal or first bars may be made from wear resistant steel of the highest grade, and the second bars may be made from tempered band steel. Since each of these second steel bars extend through the whole width of the cutting tool, no notch effect may occur and the narrow strips between the columns of holes will therefore be very strong, and cannot possibly be ruptured in normal operation.

If a rounding of the cutting edges of the die used as a cutting plate should occur after very long time of use so that they are no longer capable of making a sharp cut, the whole of the cutting plate may be surface ground until the cutting edges are again sharp and full square. This surface grinding may be repeated many times since the second steel bars may be made relatively high.

The orientation of the first and second steel bars may advantageously be different in the case of a multi-column die and a single column die respectively. Thus, according to the invention, where a multi-column punching die element is concerned, said first steel bars may suitably be located at a mutual spacing corresponding to the length of the longitudinal edges of the holes to be punched while said second steel bars have a width corresponding to the distance between the columns of holes and are located at a mutual spacing corresponding to the length of the transverse edges of the holes to be punched.

In the case of a single column punching die element, this may, according to the invention, suitably comprise two first steel bars located at a mutual spacing corresponding to the length of the transverse edges of the holes to be punched, and, for each hole of the column, two second steel bars at a mutual spacing corresponding to the length of the longitudinal edges of the holes.

A punching die made from elements of the type specified may in known manner comprise two guiding plates and one cutting plate, and, according to the invention, each of these plates may consist of a die element of the type specified.

On account of the special construction of the element, a single guide plate may be used, according to the inven tion, instead of two guide plates, in which case the die element constituting the said guide plate will be provided with second steel bars on both sides thereof.

The invention will now be described in further detail with reference to the accompanying drawings in which FIG. 1 shows one form of a niulti-colurnn punching die element according to the invention, in side View, partly in section,

FIGS. 2 and 3 plan views of the same as seen from one and the other side respectively,

FIG. 4, one form of a single column punching die element according to the invention, in plan View, and

FIG. 5 a punching die composed of two elements of the type illustrated in FIG. 4, in side View.

The punching die element illustrated in FIGS. 13 is composed of a plurality of steel bars 1 of rectangular cross section which together with intervening spacing members 2, likewise from steel, are assembled by means of bolts 3 to form a grid, as illustrated in 1 16.2. The spacing members 2 may be omitted if the steel bars 1 are held in 3 accurate positions in a jig during the further operations to be described in the following". In one face of the grid-like structure formed by the bars 1, a plurality 6f miitually parallel grooves 4, FIG. 3, are cut, cg. by means of a tiiilling cutter,- the said grooves extending across all of the bars 1 and peiietfating into the latter to a predetermined depth. A steel bar 5, FIG; 3,- is then fitted into each of the grooves 4, these steel bars extending along the whole length of the grooves as illustrated in the portion of the plate above the breaking line a in FIG. 3. The dimensions of these steel bars are so selected that they are received in the grooves 4 at a press fit so that they are firmly held therei'r'i. The composite workpiece is then surface ground whereby the outer edges of the bars 5 and the adjoining outer edges of all of the steel bars 1 will be accurately located in a common plane or in other words, the surface of the grid formed by the two systems of bars will be smooth. By this surface grind ing, the surface of the composite workpiece assumes the appearance illustrated in FIG. 3, i.e. the finished plate exhibits a plurality of rows of holes in the embodiment slidwrl 14 rows of holes, each comprising ten holes 6. In the embodiment shown, where steel spacers are provided between the steel bars 1, two steel end members 9 are also provided which are constructed with guiding holesf7 for receiving a guiding pin, and also with holes 8 for.

receiving clamping bolts. I

The cutting plate of a die may consist of a single element of the type described while the guiding plate may be composed of two such elements whichare then assembled in such a manner that the faces of the two elements in which the holes 6 are provided, are remote from one another. These holes serve to receive and guide punches or cutting needles of a Well known kind, not illustrated in the drawings. As is apparent from FIG. 2, the side of the element accdrding to the invention remote from the holes 6 has a number of open slits, corresponding to the iiui'nbsf of rows of holes, for the passage of the punches.

The single column punching die element illustrated in FIGS. 4 and 5 is composed of two steel bars 11 extending in the direction of the longitudinal edges of the holes to be punched and a plurality of steel bars 15 extending in the direction of the transverse edges of the holes. Since it would be inconvenient and result in an unnecessary great consumption of material to give the bars 15 the same width as the distance between the two holes of the row of holes, a thin bar is instead used at each end of each hole so that additional holes are formed between those used for the punching, which additional holes are of no the type illustrated in FIG. 4 with steel bars 15 fitted into both sides of the steel bars 11. This construction may also be used for a multi-column punching die composed of elements of the type illustrated in FIGS. 1-3.

used for all of the surface grinding operations required.

I claim; V

1. A punching die element for use in the punching of rectangular. holes in punched cards, comprising a plurality of first steel bars of rectangular cross section each forming in itself a complete and independent element, .said first steel bars being placed side by side at a mutual spacing to from a grid, a plurality of grooves extending side by side transversely of said steel bars across at least'one face of said grid, a second surface ground steel bar ,rsavsr forming in itself a complete and independent element and havingv a height equal to the depth of said grooves being press fitted in each of said grooves, the outer faces of said second bars and the adjoining faces of said first bar being surface ground in a common grinding operation to form a smooth grid face.

2. A multi-column punching die element for use in the punching of rectangular holes in punched cards, comprising a plurality of first steel bars of rectangular cross section placed side by side at a mutual spacing-corresponding to the lengthof the longitudinal edges of the holes to be punched, to form a grid, a plurality of grooves extending side by side transversely of said steel bars across at least one face of said grid, a second surface ground steel bar being press fitted in each of said grooves, said second steel bars having a Width corresponding to the distance between the columns of holes and being located at a mutual spacing corresponding to the length of the transverse edges of the holes to be punched, the outer faces of said second bars and the adjoining faces of said first bars being surface ground in a common grinding operation to form a smooth grid face.

3. A single column punching die element for use in the punchingof rectangular holes in punched cards comprising twd first steel bars located in parallel relationship at a mutual spacing corresponding to the length of the transverse edges of the holes to be punched, a plurality of grooves extending side by side transversely of said steel bars across at least one face thereof, a second surface ground steel bar being press fitted in each of said grooves, said second steel bars comprising, for each hole of the column, two bars at a mutual spacing corresponding to the length of the longitudinal edges of the holes, the outer faces of said second bars and the adjoining faces of said firstbars being surface ground in a common grinding operation to form a-smooth grid face.

4. A me'thdd of making a punching die element for use in the punching of rectangular holes in punched cards comprising the steps of (l) aligning a plurality of first steel bars of rectangular cross section and having a plurality of side by side grooves extending transversely across one face wherein the grooves are in registration in a plurality of lines, (2) press fitting a second plurality of steel bars into the line of grooves to form a grid defining a plurality of rectangular dies, and (3) surface grinding the grid to form a smooth grid face, whereby the dies are precisely formed to receive mating punches of standard 7 dimensions.

said second bars and the adjoining faces of said first bars in a common grinding operation to form a smooth If necessary, a plane parallel honing machine may be grid face.

7 References Cited by the Examiner UNITED STATES PATENTS 422,039 2/90 Ruger' 83679 "2,165,008 7/39 Rosenberg 76107 2,913,049 11/59 Sonier 83-553 3,100,411 8/63 Airlie 83-687 ANDREW R. JUHASZ, Primary Examiner. CARL W- TQMLIN, Examiner. 

1. A PUNCHING DIE ELEMENT FOR USE IN THE PUNCHING OF RECTANGULAR HOLES IN PUNCHED CARDS, COMPRISING A PLURALITY OF FIRST STEEL BARS OF RECTANGULAR CROSS SECTION EACH FORMING IN ITSELF A COMPLETE AND INDEPENDENT ELEMENT, SAID FIRST STEEL BARS BEING PLACED SIDE BY SIDE AT A MUTUAL SPACING TO FORM A GRID, A PLURALITY OF GROOVES EXTENDING SIDE BY SIDE TRANSVERSELY OF SAID STEEL BARS ACROSS AT LEAST ONE FACE OF SAID GRID, A SECOND SURFACE GROUND STEEL BAR FORMING IN ITSELF A COMPLETE AND INDEPENDENT ELEMENT AND HAVING A HEIGHT EQUAL TO THE DEPTH OF SAID GROOVES BEING PRESS FITTED IN EACH OF SAID GROOVES, THE OUTER FACES OF SAID SECOND BARS AND THE ADJOINING FACES OF SAID FIRST BAR BEING SURFACE GROUND IN A COMMON GRINDING OPERATION TO FORM A SMOOTH GRID FACE. 